Embodiments of the present invention refer to arrangements in remotely operated clamp connectors arranged for joining together pipes or other pipe mating equipment subsea.
More precisely, embodiments of the invention refer to an arrangement in a subsea clamp connector comprising at least two clamp segments hinged to move pivotally for tightening or widening a pipe insertion opening defined at least partially by the inner peripheries of the clamp segments. A drive screw connecting the clamp segments by threaded engagement with trunnions arranged rotatable in the pivoting ends of the clamp segments, the threads of the drive screw and trunnions turned such that the trunnions travel along the drive screw in mutually opposite directions when the drive screw is turned. The opening defined by the clamp segments is reduced when the drive screw is turned in a first or locking direction, whereas turning of the drive screw in the opposite or unlocking direction causes the clamp segments to widen the opening.
Embodiments of the present invention also refer to a method for release of a jammed subsea clamp connector.
Clamp connectors are widely used for many purposes in deep water installations, such as for joining together pipes or similar tubular members in end versus end relation, or for termination of pipes in other subsea equipment. Subsea clamp connectors can be designed for operation in horizontal as well as in vertical installation structures to provide sealed and leak-proof connection of risers, flowlines, manifolds, end terminations, pig launcher receivers etc. in the offshore oil and gas industry. To this purpose the subsea clamp connectors are usually designed internally with carefully machined surfaces to accommodate a sealing ring capable of separating the pipe content from the ambient sea, handling production pressure and seawater pressure at depths down to 1,000 meter and beyond. Metal sealing rings are typically used in subsea clamp connectors for operation at such depths. The clamp mechanism is typically supported on a backing plate and may lay exposed to the ambient sea, or may be enclosed inside a housing. The drive screw is journalled to be rotated but is arrested axially in the backing plate or housing. The drive screw can be motorized and rotated by a motor, or arranged for turning by means of an ROV (Remotely Operated Vehicle) via a tool interface, usually including a so called drive bucket, which is arranged in an accessible end of the drive screw.
Upon completed service the clamp connector is to be released and removed. Long service time in the subsea environment may occasionally cause the clamp connector to get jammed and unable to unlock through rotation of the drive screw by means of the ROV operated tool that is used for locking the clamp. In such situation alternative methods and tool arrangements are required to unlock the clamp connector in order to disconnect the pipe or equipment.
A method and tool arrangement for emergency release of a subsea clamp connector is previously disclosed in WO 2012/108775 A1. A clamp connector emergency release tool designed for subsea operation comprises a cylindrical hole-saw which is rotated by a motor and advanced axially into the clamp connector by means of a piston and cylinder assembly. The hole-saw separates the drive screw together with fragments of the clamp segments and trunnions, whereupon the remainders of the clamp segments are free to pivot from the locking position. The hole-saw is installed in an adapter arranged to be connected to the clamp connector, the adapter and clamp connector fitted for engagement with each other.
Methods and arrangements for emergency release of coupled structural elements are previously known also from other technical fields and applications. These methods and arrangements may include explosive fasteners that are installed in structures adapted through a dedicated design that allows separation of the structures upon detonation of an explosive charge built into the fastener.